1. Field of the Invention
This invention relates to a cylinder lock, more particularly, to a cylinder lock having improved structural strength.
2. Description of the Related Art
A cylinder lock typically includes a drive mechanism connected to inner and outer handles and including a latch retractor to retract a latch unit which can latch or unlatch a door. The drive mechanism generally includes a shell receiving a retractor case that contains the latch retractor, and inner and outer drive spindles connected respectively to the inner and outer handles. The inner and outer drive spindles extend into the shell and connect the latch retractor so that the latch retractor can be operated through the inner drive spindle and the inner handle, or through the outer drive spindle and the outer handle. The latch retractor is biased by a biasing spring so that the latch unit is normally moved to a latching position. When the latch retractor is operated by rotating the inner or outer handle, the latch retractor retracts the latch unit to an unlatching position.
Among the components of such a cylinder lock, the outer drive spindle and the retractor case are most liable to be damaged due to frequent rotation of the handles or due to improperly or destructively applied external forces. Improvements have been suggested in the art to strengthen such cylinder locks. An example thereof is disclosed in U.S. Pat. No. 6,893,059.